Octet Rule = atoms tend to gain, lose or share electrons so as to have 8 electrons

C would like to N would like toO would like to

Gain 4 electronsGain 3 electronsGain 2 electrons

Electron Dot Structures

Symbols of atoms with dots to represent the valence-shell electrons

1 2 13 14 15 16 17 18

H He:

Li Be B C N O : F :Ne :

Na Mg Al Si P S :Cl :Ar :

Chemical bond

• A chemical bond forms when outer-shell electrons of different atoms come close enough to each other to interact and rearrange themselves into a more stable arrangement.

Types of Chemical Bonds

• Ionic bonds formed when metal atoms combined with non-metal atoms

• Metallic bonds formed when metal atoms combined with metal atoms.

• Covalent bonds formed when non-metal atoms combined with non-metal atoms.

Ionic Compounds

1). Ionic bond – electron from Na is transferred to Cl, this causes a charge imbalance in each atom. The Na becomes (Na+) and the Cl becomes (Cl-), charged particles or ions.

How many chlorine ions surround each sodium ion and vice versa?

NaCl coordination number- 6:6

The coordination number of an ionic lattice is writtenas a ratio x:y

Hardness and Brittleness

Figure 6.4 Figure 6.4 The repulsion The repulsion between like charges between like charges causes this sodium causes this sodium chloride crystal to chloride crystal to shatter when it is hit shatter when it is hit sharply.sharply.

Electrical Conductivity

• In the solid form, ions in sodium chloride are held in the crystal lattice and are not free to move so cannot conduct electricity.

• When the solid melts the ions are free to move. • In a similar way, when sodium chloride dissolves

in water, the ions separate and are free to move towards the opposite charge.

Properties of Ionic Compounds

– Forms crystal composed of 3d array of ions (ionic network lattice)

– Have high melting and boiling temperatures.

– Are hard but brittle

– Do NOT conduct electricity in the solid state

– They will only conduct electricity if they are melted or dissolved in water.

Structure

• From the properties we can conclude:– The forces between the particles are strong.– There are no free-moving electrons present,

unlike in metals.– There are charged particles present, but in solid

state they are not free to move. – When an ionic compound melts, however, the

particles are free to move and the compound will conduct electricity.

Use Electron shell diagram and simple equation to show the formation of:

• NaCl

• MgO

Naming Binary Ionic CompoundsContain 2 different elements

Name the metal first, then the nonmetal as -ide.

Examples:

NaCl sodium chloride

ZnI2 zinc iodide

Al2O3 aluminum oxide

Practise

Complete the names of the following binary compounds:

Na3N ________________

KBr ________________

Al2O3 ________________

MgS _________________________

Solution

Complete the names of the following binary compounds:

Na3N sodium nitride

KBr potassium bromide

Al2O3 aluminum oxide

MgS magnesium sulfide

Transition Metals

Many form 2 or more positive ions

1+ 2+ 1+ or 2+ 2+ or 3+

Ag+ Cd2+ Cu+, Cu2+ Fe2+, Fe3+

silver cadmium copper(I) ion iron(II) ion

ion ion copper (II) ion iron(III) ion

Zn2+

zinc ion

Write symbols for these:• Potassium ion

• Magnesium ion

• Copper (II) ion

• Chromium (VI) ion

• Barium ion

• Mercury (II) ion

Formula of ionic compounds

Criss-Cross MethodCriss-Cross Method

1.1. Write the symbols for the ions side by side. Write Write the symbols for the ions side by side. Write the cation first.the cation first.• AlAl3+3+ OO2-2-

1.1. Write the symbols for the ions side by side. Write Write the symbols for the ions side by side. Write the cation first.the cation first.• AlAl3+3+ OO2-2-

2.2. Cross over the charges by using the absolute value Cross over the charges by using the absolute value of each ion’s charge as the subscript for the other of each ion’s charge as the subscript for the other ion.ion.• AlAl22 OO33

3. Check the subscripts and divide them by their 3. Check the subscripts and divide them by their largest common factor to give the smallest possible largest common factor to give the smallest possible whole-number ratio of ions. Then write the whole-number ratio of ions. Then write the formula.formula.• AlAl22OO33

• For Al: 2 x 3For Al: 2 x 3++ = 6 = 6++ For O: 3 x 2For O: 3 x 2-- = 6 = 6--

2.2. Cross over the charges by using the absolute value Cross over the charges by using the absolute value of each ion’s charge as the subscript for the other of each ion’s charge as the subscript for the other ion.ion.• AlAl22 OO33

3. Check the subscripts and divide them by their 3. Check the subscripts and divide them by their largest common factor to give the smallest possible largest common factor to give the smallest possible whole-number ratio of ions. Then write the whole-number ratio of ions. Then write the formula.formula.• AlAl22OO33

• For Al: 2 x 3For Al: 2 x 3++ = 6 = 6++ For O: 3 x 2For O: 3 x 2-- = 6 = 6--

Example 1: Calcium and OxygenExample 1: Calcium and Oxygen

Calcium Ca2+ Ca2+

Oxide O2-

O2-

Ca2O2

Criss-Cross Method

CaO

Example 2: Magnesium and PhosphorusExample 2: Magnesium and Phosphorus

Magnesium

Mg2

+

Mg2

+

Phosphorus

P3-

P3-

Mg3P

2

Criss-Cross Method

The sum of the cation charge and the sum of the anion charge The sum of the cation charge and the sum of the anion charge must cancel each other so that the compound formed is must cancel each other so that the compound formed is neutral.neutral.

Practise

1. The formula for the ionic compound of

Na+ and O2- is

1) NaO 2) Na2O 3) NaO2

2. The formula of a compound of aluminum and chlorine is

1) Al3Cl 2) AlCl2 3) AlCl3

3. The formula of Fe3+ and O2- is

1) Fe3O2 2) FeO3 3) Fe2O3

Solution

A. The formula for the ionic compound of Na+ and O2- is

2) Na2O

B. The formula of a compound of aluminum and chlorine is

3) AlCl3

C. The formula of Fe3+ and O2- is

3) Fe2O3

Sample Problem 7-1

•Write the formulas for the binary ionic compounds Write the formulas for the binary ionic compounds formed between the following elements:formed between the following elements:

A. lithium and fluorineB. lithium and oxygen

Names of Variable Ions

Use a roman number after the name of a metal that forms two or more ions

Transition metals and the metals in groups 4A and 5A

FeCl3 (Fe3+) iron (III) chloride

CuCl (Cu+ ) copper (I) chloride

SnF4 (Sn4+) tin (IV) fluoride

PbCl2 (Pb2+) lead (II) chloride

Fe2S3 (Fe3+) iron (III) sulfide

II. Stock system (roman numerals)

Example:Example:

Fe2+

• Iron(II)Iron(II)

Fe3+

• Iron(III)Iron(III)

CuCl• copper(I) chloridecopper(I) chloride

CuCl2• copper(II) chloridecopper(II) chloride

Sample Problem 7-2

a. Write the formula and give the name for the a. Write the formula and give the name for the compound formed from the ions Crcompound formed from the ions Cr3+3+ and F and F--..

b. Write the name for Cub. Write the name for Cu33NN22..

Fe [Ar] 3d64s2

Fe2+ [Ar] 3d6

Fe3+ [Ar] 3d5

Here are the changes in the electronic structure of iron to make the 2+ or the 3+ ion.

Learning Check

Complete the names of the following binary

compounds with variable metal ions:

FeBr2 iron (_____) bromide

Cu2O copper (_____) oxide

SnCl4 ___(_____ ) ______________

Fe2O3 ________________________

CuS ________________________

Solution

Complete the names of the following binary

compounds with variable metal ions:

FeBr2 iron ( II ) bromide

Cu2O copper ( I ) oxide

SnCl4 tin (IV) chloride

Fe2O3 iron (III) oxide

CuS copper (II) sulfide

Learning Check

Name the following compounds:A. CaO

1) calcium oxide 2) calcium(I) oxide3) calcium (II) oxide

B. SnCl4 1) tin tetrachloride 2) tin(II) chloride 3) tin(IV) chloride

C. Co2O3

1) cobalt oxide 2) cobalt (III) oxide3) cobalt trioxide

Solution

Name the following compounds:

A. CaO 1) calcium oxide

B. SnCl4 3) tin(IV) chloride

C. Co2O3 2) cobalt (III) oxide

Learning Check

Write the correct formula for the compounds containing the following ions:

A. Na+, S2-

1) NaS 2) Na2S 3) NaS2

B. Al3+, Cl-

1) AlCl3 2) AlCl 3) Al3Cl

C. Mg2+, N3-

1) MgN 2) Mg2N3 3) Mg3N2

Solution

A. Na+, S2-

2) Na2S

B. Al3+, Cl-

1) AlCl3

C. Mg2+, N3-

3) Mg3N2

Practise

Na2O K2S MgBr2 AlN Ba3As2

CaCl2 AgCl AlH3 ZnI2 Li3P

Name the following ionic compounds:

Nomenclature of binary ionic compounds

Na2O = sodium oxide K2S = potassium sulfide

MgBr2 = magnesium bromide AlN = aluminum nitride

Ba3As2 = barium arsenide CaCl2 = calcium chloride

AgCl = silver chloride AlH3 = aluminum hydride ZnI2 = zinc iodide Li3P = lithium phosphide

Answers:

III. Polyatomic Ions

A A chargedcharged group of group of covalentlycovalently bonded bonded atomsatoms Combine with ions of opposite charge to form Combine with ions of opposite charge to form

ionic compoundsionic compounds

Ex: NHEx: NH44++, NO, NO33

--, SO, SO442-2-

Nomenclature of binary ionic compoundsSome polyatomic anions that you must know:

NO3- = nitrate NO2

- = nitrite

SO4 2 - = sulfate SO3

2- = sulfite

PO43- = phosphate PO3

3- = phosphite

CO32- = carbonate

HCO31- = hydrogen carbonate or

bicarbonate

OH- = hydroxide CN- = cyanide

C2H3O2- = acetate C2O4

2- = oxalate

III. Polyatomic IonsIII. Polyatomic Ions

Most commonMost common ion is given the ending ion is given the ending –ate–ate..Most commonMost common ion is given the ending ion is given the ending –ate–ate..

ClO3-ClO3-

• chloratechlorate• chloratechlorate ClO2-ClO2-

• chloritechlorite• chloritechlorite ClO-ClO-• hypochloritehypochlorite• hypochloritehypochloriteClO4

-ClO4-

• perchlorateperchlorate• perchlorateperchlorate

• One less oxygenOne less oxygen than than –ate–ate ends inends in –ite–ite..• One less oxygenOne less oxygen than than –ate–ate ends inends in –ite–ite..

• One less oxygenOne less oxygen than than –ite–ite is given the prefixis given the prefix hypohypo..

• One less oxygenOne less oxygen than than –ite–ite is given the prefixis given the prefix hypohypo..• One more oxygenOne more oxygen than than -ate-ate is given the prefixis given the prefix perper..

• One more oxygenOne more oxygen than than -ate-ate is given the prefixis given the prefix perper..

NO3-NO3-

• nitratenitrate• nitratenitrate NO2-NO2-

• nitritenitrite• nitritenitrite

Sample Problem 7-3

a. Write the formula for potassium sulfate.a. Write the formula for potassium sulfate.

b. Write the formula for calcium carbonate.b. Write the formula for calcium carbonate.

c. Write the formula for tin(IV) sulfate.c. Write the formula for tin(IV) sulfate.

potassium chloride

magnesium nitrate

copper(II) chloride

K+ Cl

Mg2+ NO3

Cu2+ Cl

KCl

Mg(NO3)2

CuCl2

Ionic Nomenclature Practice

Nomenclature of binary ionic compounds

NaHCO3 K2SO3 MgSO4 KCN H2PO4

Ca(OH)2 NH4NO3 Zn(NO3)2 Li3PO4 HNO3

Naming salts composed of the polyatomic ions is the same as with the monatomic anions. Metal name then polyatomic name.

NaOH sodium hydroxide Ba(NO3)2 barium nitrateH2SO4 hydrogen sulfate CsNO2 cesium nitrite

Sometimes there is a common name:KHCO3 potassium hydrogen carbonate or potassium bicarbonate

Note: the polyatomic anions must be memorized.

Name the following ionic compounds: